Injector duty cycle.....
Thread Starter
Team Owner
Joined: Mar 2000
Posts: 83,383
Likes: 87
From: Boston, MA
Injector duty cycle.....
...is this correct?
Batchfire:
(Pulsewidth * RPM ) / 600 = DC
Sequential:
(Pulsewidth * RPM ) / 1200 = DC
If so then at WOT I'm around 81% @ 5400 and 90% @ 6000.
Batchfire:
(Pulsewidth * RPM ) / 600 = DC
Sequential:
(Pulsewidth * RPM ) / 1200 = DC
If so then at WOT I'm around 81% @ 5400 and 90% @ 6000.
Former Vendor
Joined: Jun 2001
Posts: 7,204
Likes: 6
From: St Marys PA
Re: Injector duty cycle..... (scorp508)
Scorp, Yes that is correct.
As RPMs increase the time available 600/RPM decreases.
At 5400 RPM you have 600/5400= 11.11msec to fuel.
At 6000 RPM you have 600/6000=10 msec
If the base pulse width becomes greater than your time available, you are then static.
But remember you can alway turn up your fuel pressure a few pounds, readjust your injector constant, and your pulse widths will decrease significantly.
Clear as mud right. :D :cheers:
As RPMs increase the time available 600/RPM decreases.
At 5400 RPM you have 600/5400= 11.11msec to fuel.
At 6000 RPM you have 600/6000=10 msec
If the base pulse width becomes greater than your time available, you are then static.
But remember you can alway turn up your fuel pressure a few pounds, readjust your injector constant, and your pulse widths will decrease significantly.
Clear as mud right. :D :cheers:
Le Mans Master
Joined: Jul 2000
Posts: 5,012
Likes: 5
From: OKC OK
Re: Injector duty cycle..... (scorp508)
I was looking for the same info the other day and here is what I found....
Duty cycle is your pulse width, divided by the time available in two crank revolutions, so you need to know an RPM along with the pulse width to determine if the injector is being max'd out (greater than 90% duty cycle).
At 6,000RPM the time available in two crank revs is 20mS. So if you see an 18mS pulse width at 6,000RPM, your duty cycle is:
18 / 20 = 0.90 = 90%.
As a guideline, maximum possible pulse width vs. RPM:
5,000rpm - 24.0mS (80%DC = 19.2mS)
5,500rpm - 21.8mS (80%DC = 17,5mS)
6,000rpm - 20.0mS (80%DC = 16.0mS)
6,500rpm - 18.4mS (80%DC = 14.7mS)
7,000rpm - 17.1mS (80%DC = 13.7mS)
7,500rpm - 16.0mS (80%DC = 12.8mS)
Duty cycle is your pulse width, divided by the time available in two crank revolutions, so you need to know an RPM along with the pulse width to determine if the injector is being max'd out (greater than 90% duty cycle).
At 6,000RPM the time available in two crank revs is 20mS. So if you see an 18mS pulse width at 6,000RPM, your duty cycle is:
18 / 20 = 0.90 = 90%.
As a guideline, maximum possible pulse width vs. RPM:
5,000rpm - 24.0mS (80%DC = 19.2mS)
5,500rpm - 21.8mS (80%DC = 17,5mS)
6,000rpm - 20.0mS (80%DC = 16.0mS)
6,500rpm - 18.4mS (80%DC = 14.7mS)
7,000rpm - 17.1mS (80%DC = 13.7mS)
7,500rpm - 16.0mS (80%DC = 12.8mS)
Thread Starter
Team Owner
Joined: Mar 2000
Posts: 83,383
Likes: 87
From: Boston, MA
Re: Injector duty cycle..... (ski_dwn_it)
But remember you can alway turn up your fuel pressure a few pounds, readjust your injector constant, and your pulse widths will decrease significantly.
Former Vendor
Joined: Jun 2001
Posts: 7,204
Likes: 6
From: St Marys PA
Re: Injector duty cycle..... (LT4POWR)
As a guideline, maximum possible pulse width vs. RPM:
5,000rpm - 24.0mS (80%DC = 19.2mS)
5,500rpm - 21.8mS (80%DC = 17,5mS)
6,000rpm - 20.0mS (80%DC = 16.0mS)
6,500rpm - 18.4mS (80%DC = 14.7mS)
7,000rpm - 17.1mS (80%DC = 13.7mS)
7,500rpm - 16.0mS (80%DC = 12.8mS)
5,000rpm - 24.0mS (80%DC = 19.2mS)
5,500rpm - 21.8mS (80%DC = 17,5mS)
6,000rpm - 20.0mS (80%DC = 16.0mS)
6,500rpm - 18.4mS (80%DC = 14.7mS)
7,000rpm - 17.1mS (80%DC = 13.7mS)
7,500rpm - 16.0mS (80%DC = 12.8mS)
But Scorp is a batch fire which is basically 1/2 the time alotted opposed to your setup. => 600/RPM
Here is a reprsentation of what Scorp have available:
Taken from one of my other posts:
RPM BPW TIME AVAIL
2200 11.67 27.3
3475 14.31 17.3
4150 13.85 14.5
4525 13.43 13.3
4900 12.74 12.2
5125 12.52 11.6
5075 12.48 11.8
4975 12.67 12.1
5075 12.41 11.8
5275 12.13 11.4
5300 11.87 11.3
5450 11.23 11.0
5825 11.03 10.3
5850 10.57 10.3
6075 10.42 9.9
6175 10.39 9.7
6300 10.24 9.5
6375 10.08 9.4
Anytime BPW is greater than time available you are static.
Determine your duty cycle by DC = (BPW x RPM)/600
For your sequential its the same only using 1200 in the forumals. Or simply multiply these answers by two, since the firing sequence allows for 2x the amount of time with sequential fire.
Hope we are all clear now.
:cheers: :thumbs:
